This is the continuation of research project NS 09871, entitled neuropharmacology-anesthesia and the Nervous System. Future progress in Anesthesiology will depend heavily upon basic research in Neuropharmacology. The studies will center about neurological responses to anesthetics emphasizing the value of the spinal cord in such neuropharmacological research. The research projects proposed herein are direct extensions of the previous studies as well as considerable departure from past approaches, and are aimed at the study of spinal cord function modulated by anesthetics while physiological parameters are strictly maintained within normal range. The departure from past approaches defined below show our new direction. The study utilizing extra cellular single unit recording technique falls into three major categories: (1) effects of anesthetics on the dorsal horn spinal gray laminae and nuclear aggregates of feline lumbar spinal cord, (2) effects of anesthetics on nucleus reticularis gigantocellularis and (3) effects of anesthetics on nucleus caudalis of trigeminal complex. BIBLIOGRAPHIC REFERENCES: The effects of halothane and sodium thiopental on the spontaneous and evoked activity of dorsal horn cells. Kitahata, L. M, Ghazi-Saidi, K., Yamashita, M., Taub, A.,Bonikos, C. and Kosaka Y. Federation Proceedings 34:771, 1975. Modes and sites of "analgesic" action of anesthetics on the spinal cord. Kitahata, L. M. International Anesthesiology Clinics 13:149-170, 1975.